Forums > Jitter

stacking multiple

July 27, 2012 | 4:06 pm

I’ve got a chain of slabs that I like, is there any advantage processor efficiency wise to taking those shaders and compiling them down to a single slab?

July 27, 2012 | 5:04 pm

There can be. It really depends on how big the one shader gets versus how how much your graphics card can handle. There really isn’t an exact rule.

July 27, 2012 | 5:14 pm

It’s a suck it and see situation? Cheers.

July 27, 2012 | 5:23 pm


July 27, 2012 | 5:25 pm

sounds like a good opportunity to try out

July 28, 2012 | 8:08 pm

Indeed it was… have to say having forced myself to sit and play with that it is a truly awesome addition to jitter. Being able to fiddle with shaders in graphical land or use codeboxes as required rather than code in textedit and then reload your slab is well wicked, you can just reroute the output to whatever bit of the patch you’re trying to understand, so quick to muck about with.

Very tasty.

July 28, 2012 | 11:41 pm

How do you know when you’ve reached the limit your card can handle, right now I’ve got a shader that does scale bias, brightness, contrast and saturate. When I try to add more (I want a colour splitter and a ripple repos) I start by adding a [sample] but it won’t let me connect to it.

Also I start getting messages at the max window that lua isn’t happy.

Does this mean I’ve filled this shader?

July 30, 2012 | 5:44 pm

Does this mean I’ve filled this shader?

no, it means you’re likely found a bug. Can you post the patch that causes problems?

July 31, 2012 | 12:32 pm

It’s bigger than the sun, here is just the shader, it’s not posting any errors to the max window anymore but it still won’t let me resample the output of the first stage.

— Pasted Max Patch, click to expand. —
July 31, 2012 | 12:33 pm


  1. rmpripple.genjit
July 31, 2012 | 3:13 pm

In the gen world, the only thing you connect to the input of [sample] is an [in] operator. It won’t let you connect anything else by design. The [in] operators represent two different concepts simultaneously, which is probably what’s causing some confusion. They are:

1) The current pixel/cell being processed
2) a proxy for the entire input matrix/texture

When you connect [in] to any operator except [sample], you’re connecting the current pixel being processed to that operator (1). When you connect [in] to [sample], you’re connecting the entire input matrix to it (2). This is because [sample] can pull an arbitrary pixel from a given input. All other ops can only work with the current pixel flowing through the gen patcher.

In your genjit patches, I noticed you had [in 1] -> [sample] with a [norm] connected to the second [sample] inlet. You actually don’t need this. The following are equivalent:

— Pasted Max Patch, click to expand. —
— Pasted Max Patch, click to expand. —

If you run the two gen patchers above, you’ll see that using [sample] in this way and simply passing through [in] are the same.

If you want to chain effects like a brcosa and then a repos type displacement, you’ll have to chain separate gl.pix objects together. You can’t sample from anything except the input, so you can’t sample from the end of a processing chain like you were trying to do. The entire processed image simply isn’t available at that time.

Hope this all makes sense. If anything is confusing, please ask.

July 31, 2012 | 6:00 pm

That makes sense (as much as anything shader related does).

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